Spay it Ain't So

It's rare for Animal Sheltering to report on a study intended to shed light on human health, but when that study has the potential to affect a fundamental practice of the animal welfare field—spay/neuter—all bets are off.

Aging Cell is a scientific journal in the U.K. that focuses on the biology of human aging. In the October 2009 issue, it published “Exploring mechanisms of sex differences in longevity: lifetime ovary exposure and exceptional longevity in dogs.” The study was designed to shed more light on the gender differences in human longevity—specifically, why women live longer than men.

Researchers studied a group of 119 very old rottweilers in North America—all pet dogs, all with varying spay histories—and compared them to another group of 186 rottweilers who had typical lifespans. Like women, the researchers write, female dogs were more likely than males to achieve exceptional longevity. “However, removal of ovaries during the first 4 years of life … erased the female survival advantage over males. In females that retained their ovaries for more than 4 years, likelihood of exceptional longevity increased to more than three times that of males.”